From IMDB

This film came out in 1944, the same year David O. Selznick released Since You Went Away (1944). Part of the campaign for the latter film were major ads that declared, "'Since You Went Away' are the four most important words in movies since 'Gone With the Wind'!" which Selznick had also produced. Wilder hated the ads and decided to counter by personally buying his own trade paper ads which read, "'Double Indemnity' are the two most important words in movies since 'Broken Blossoms'!" referring to the 1919 'D.W. Griffith' classic. Selznick was not amused and even considered legal action against Wilder. Alfred Hitchcock (who had his own rocky relationship with Selznick) took out his own ads which read, "The two most important words in movies today are 'Billy Wilder'!"

Baby.

The "third act" is precisely where a pretty ordinary crime, with a broken leg in the way in more senses than one, turns and twists into a noir triple-crosser.

Respect for Billy Wilder ...